SignalR, ASP.NET 5 and CORS - signalr

Question

I'm trying to use SignalR with my MVC6 application, but I encounter problem with CORS.
First : If I host my index.html file on http://localhost:1234/index.html (same as my web app) it's working.
But when I host it elsewhere (for example in file:///C:/Users/me/Documents/index.html), I have this error :
No 'Access-Control-Allow-Origin' header is present on the requested
resource. Origin 'null' is therefore not allowed access.
Of course, I try to enable CORS, this is my startup file :
public class Startup
{
public void ConfigureServices(IServiceCollection services)
{
services.AddMvc();
services.AddSignalR();
services.AddCors();
var policy = new Microsoft.AspNet.Cors.Core.CorsPolicy();
policy.Origins.Add("*");
policy.Headers.Add("*");
policy.Methods.Add("*");
services.ConfigureCors(x => x.AddPolicy("allowall", policy));
}
public void Configure(IApplicationBuilder app)
{
app.UseCors("allowall");
app.UseSignalR();
app.UseMvc();
}
}
But now, I have another error :
A wildcard '*' cannot be used in the 'Access-Control-Allow-Origin'
header when the credentials flag is true. Origin 'null' is therefore
not allowed access.
Then I try with :
policy.SupportsCredentials = false;
but still getting same error.
What should I do ?

Answer 1

Seen with SignalR team, this is working on http://localhost:port but not on file:///C:/Users/me/Documents/index.html and this is normal.